The system identifier, a URI reference [
IETF RFC 2396], for this
input source. The system identifier is optional if there is a byte
stream, a character stream, or string data. It is still useful to
provide one, since the application will use it to resolve any
relative URIs and can include it in error messages and warnings. (The
LSParser will only attempt to fetch the resource identified by the
URI reference if there is no other input available in the input
source.)
If the application knows the character encoding of the object
pointed to by the system identifier, it can set the encoding using
the
encoding
attribute.
If the specified system ID is a relative URI reference (see
section 5 in [
IETF RFC 2396]), the DOM
implementation will attempt to resolve the relative URI with the
baseURI
as the base, if that fails, the behavior is
implementation dependent.